When I refer herein to an electronic music synthesizer, I am referring to a unit capable of receiving signals from some kind of controller which directs the unit to electronically synthesize a tone or modulate or modify it in accordance with the instructions or signals from the controller and/or in accordance with preprogrammed modes. The preferred electronic music synthesizer is the programmable apparatus described in the aforementioned patent, while the typical application of a keyboard for such a music synthesizer is described in the copending application also identified above.
In the past, electronic music synthesizers have principally been the domain of keyboard players because it was relatively easy to design switching-type keyboards as inputs for music synthesizers. However, guitar players and musicians concerned with versatility also have evidenced the desire to be able to provide greater inputs for electronic music synthesizers utilizing the standard guitar-playing techniques.
In my copending application Ser. No. 560,942 filed Oct. 13, 1983 and now U.S. Pat. No. 4,580,479, I have described a sophisticated guitar controller for an electronic music synthesizer having a degree of versatility and an assortment of controls which were capable of delivering expression, note selection, amplitude and modulating information to the synthesizer. This system, however, required the highly specialized constructions of string simulators and fret simulators which were not always satisfactory for a natural feel to the guitar player.
It is thus highly desirable to be able to provide a guitar controller having a more natural feel and especially one which can use the strings and frets of a guitar to provide the information required for the music synthesizer.
Other desiderata of such a controller include the ability to work through a standard MIDI (Music Instrument Digital Interface), i.e. the standard format adopted by the music industry for inputs to electronic music generating systems.
In the past, as will be apparent from the discussions of the critical components of a guitar controller in accordance with the invention below, efforts have been made to utilize the string and fret combinations of signals for the note selection. These systems have concentrated upon electronics which have utilized each string and fret junction as a switch and systems which have provided resistance bridges including the string resistance between a pair of frets and resistances in series with each of the frets simultaneously contacted by a respective string to signal, e.g. via a scanning system, fret acquisition and, therefore, for the depressed string, the respective note represented by the free-length of the string between the bridge and the lowest of the frets engaged by the depressed string.
Various techniques have been utilized to signal which of the strings were depressed as well.
All of these earlier systems are fraught with various problems and drawbacks obviated by the present invention and some of which will be detailed below.
At this point it is merely important to note that critical to the accurate operation of the fret acquisition system, i.e. detecting the lowest fret against which a spring may be depressed on the key fret, is the fact that this detection must be devoid of the problems which can occur if electrical contact between the conductive string and the conductive fret develops a resistance which somehow interferes with the ability to accurately determine the selected fret.
In early experiments with the approach in which a bridge is formed by the resistance of a string between two frets with which it is in contact, the resistances of these frets, such contact resistance was found to be prohibitively large, at least with long-term use of the instrument and the passage of the comparatively high electric currents through the strings which were required to generate an adequate potential difference for measurement of fret resistance. Consequently, while fret resistance provided a theoretical possibility for fret acquisition, in practical terms fret acquisition utilizing a resistance determination was found to be unsatisfactory even when expensive expedients were followed to make the contact of as low resistance type as possible.